Electrical instrument



Sept. 2, 1941. R. M. SMITH ET AL ELECTRICAL INSTRUMENT Filed Aug. 18,1339 2 Sheets-Sheet l INVENTORS Rag M 51772272 and WITNESSES:

ATTOR Y ept. 2, 1941. R. M. SMlTH EFAL 2,254,920

I ELECTRICAL INSTRUMENT Filed Aug. 18, 1939 2 Sheets-Sheet 2 WITNESSES: INVENTORS I Ray M 51722272 and gal/774 72 Pz'esz.

Patented Sept. 2, 1941 ELEGTPIGAL INSTRUMENT Roy M. Smith, Livingston,

Gillette, N. J., assignors to and Kolman Riesz, Westinghouse Electric d; Manufacturing Company, East Pittsburgh, 1 s., a corporation of Pennsylvania Application August 13, 1939, Serial No. 290,768

4 laims.

This invention relates to electrical instrinnents, and it has particular relation to detachable instruments which be readily mounted operative position and detached tr erefrom.

Detachable electrical instruments have been widely accepted in certain restricted fields such as those including wa tthour meters and ing instruments as exemplified by the constructions shown in the Bradshaw et al. Patent No. 1,969,499, and the Young et a1. Patent No. 2,128,- 277. The constructions thus far employed are particularly suited for electrical instruments having a relatively light weight.

Certain advantages make the detachable construction particularly desirable for electrical instruments having large numbers of contacts, such as relays. Such instruments ordinarily are mounted on switchboards having complicated wiring extending over the rear of the switchboard panel. When relays of conventional construction are employed, the relay is connected permanently circuit with the switchboard wiring. Consequently, to mount a standard conventional relay on a switchboard it is necessary first to attach the relay to the front of a switchboard panel. Subsequently, a workman must proceed behind the switchboard panel to connect the relay terminals to the switchboard circuits. Conversely, in order to remove he relay from the switchboard panel for servicing or replacement, it is necessary for a workman first to proceed behind the switchboard panel to disconnect the numerous relay connections to the switchboard circuits. Then the workman must return to the front of the switchboard panel in order to detach the relay therefrom. Not only does this procedure entail an objectionable amount of labor and time, but the operations carried on in the complex wiring at the rear of the switchboard are accompanied by d nger to the workman and switcher d of 1g. disadvantages are obviated by the utilisation of the detachable construction for relays, but a number of problems and dizhculties presented.

Among the problems presented, by relays and a number of other electrical devices, is weight, which, in the case of protective relays, for example, is substantial and requires a sturdy support. Furthermore, such instruments often have an extremely large number of electrical contacts to be connected in the switchboard circuits; as many as twenty-three being required on a standard type of transmission line protective relay.

In the detachable construction, the frictional resistance between the contact jaws carried by the switchboard and the contact blades on the instrument may reach such high value that insertion and removal of the instrument contacts are difiicult. Also the necessity for placing a large number of contacts in a compact assembly renders the alignment of contacts difficult.

A still further problem is presented in certain instruments, such as relays, because of the different types of mounting encountered. For example, relays are made in both flush and projection styles. he flush relay is mounted in an opening provided in a switchboard or other panel with its cover face substantially flush with the face of the panel. On the other hand, a projection relay is mounted on a switchboard or other panel with its base substantially flush with the surface of the panel. A detachable construction should be applicable to all styles of instruments insofar as possible.

In accordance with our invention, a switchboard or other panel is provided with guide means for controlling the insertion of a detachable electrical instrument into its mounted position. This guide, in a preferred embodiment, is employed for supporting a number of fixed contacts for detachably engaging contacts carried by the electrical instrument. Additionally, the guide serves to assure proper alignment of the fixed and movable contacts as the electrical instrument is mounted on and removed from the panel. "With minor modifications, the contact structure designed in accordance with our invention may be employed either for flush or for projection mounting. In order to overcome the contact resistance during insertion and removal of a detachable instrument in one specific embodiment of our invention, we provide jack-screws for forcing the detachable instrument into and out 1 its mounted position.

It is, therefore, an object of our invention to provide a detachable instrument assembly having means for guiding the detachable instrument into its mounted position.

It is a further object of our invention to provide a detachable instrument assembly having adequate means for supporting it during insertion, removal and operation of the instriunent.

It is a further object of our invention to provide a detachable electrical instrument assembly having means for assuring alignment of the instrument contacts with fixed contacts during insertion or removal of the instrument from its mounted position.

It is another object of our invention to provide a detachable instrument construction which is suitable for both projection and flush mounting.

t is another object of our invention to provide a detachable electrical instrument assembly with means for facilitating movement of the detachable instrument into and out of its mounted position.

It is still a further object of our invention to provide a detachable instrument assembly having contact elements carried by the instrument for engagement with fixed contacts with means for applying a stress directly between the instrument structure and the holder for the fixed contacts in order to facilitate movement of the detachable instrument from and toward its mounted position.

Other objects of our invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a view in perspective of a flush type detachable instrument assembly,

Fig. 2 is a view in top plan with parts in section of the detachable instrument assembly illustrated in Fig. 1,

Fig. 3 is a view in rear elevation with parts broken away of a detachable instrument assembly similar to that shown in Fig. 1, and

Fig. 4 is a view in side elevation, partly in section, of a projection type of detachable instrument assembly.

Referring to the drawings and particularly to Figs. 1 and 2, we have illustrated an electrical instrument casing I which may be of the rectangular style often employed for electrical relays. In the specific embodiment illustrated the casing comprises a wall portion 2, a rear base member 3 and a front flange member 4. These various portions may be united by means of screws, welding or other suitable attaching means or may be of integral construction. A cover 5, which may be of glass, is provided for the front of the casing and may be removably held in position by means of suitable screw means 6. tion thus far described may vary appreciably in shape, materials and construction. If desired, the wall portion 2 need not be a complete enclosure but may constitute structural members extending between the base member 3 and the flange member 4. In a specific design, the base member 3 may be a metal die-casting, the wall portion 2 and the flange member 4 may be formed from thin sheet steel. This casing is intended to house an electrical instrument such as an electrical relay.

In order to establish contacts between the electrical relay and external circuits, a plurality of contact members I are provided at any suitable point such as the base member 3. For example, the base member may be provided with one or more pairs of ribs 8 connected at intermediate points by means of a web 9. This web is provided with a plurality of openings I 0 through which the contact members I pass. Each contact mem her 1 includes an insulating cylindrical sleeve II having a square base portion I2. The purpose of the square base portionis to prevent rotation of the contact member in the web 9. In order to retain the contact member I in the web 9, the

sleeve I! may be provided with a cylindrical groove I3 adjacent the web 9. By placing a spring split-ring I4 in this groove with a portion projecting over the Web 9, the contact member.

The casing constructhe casing I is mounted on a panel I! which may be a switchboard panel, the front of a box, the cover of a trough, or any other suitable structure. Since the casin I is of the flush mounted type, the panel I? is provided with an opening I8 through which the base member 3 and the wall portion 2 may be inserted. As above noted, casings of this type and their contents often are of considerable length and of great width. As the casing is inserted in its mounted position, the portion of the casing available from the front of the panel I? for handling may be relatively small, and it is difficult to maintain the casing and its contents in proper position. For this reason we prefer to provide a supporting element I9 for engaging a face of the relay during its insertion in order to maintain the relay and its casing in proper position. Although the one support I9 would materially assist in supporting the relay casing I, we prefer to provide a second support 28 for engaging a second portion of the relay casing. In the specific embodiment illustrated, the supports I9 and 20 constitute two legs of a U- shaped member or bracket 2|, the legs being connected together at one end by a connecting section 22. The legs I9 and 2b with the connecting section 22 thus form a U-shaped bracket which may be attached to the panel I? in any conventional manner.

In the embodiment illustrated, the ends of the legs I9 and 20 are bent at right angles and attached in any suitable way to reinforcing straps 23 as by welding. These straps, in turn, are attached in any suitable way to the panel IT, a plurality of machine screws 24 being illustrated for this purpose. Further accuracy in guiding is provided by forming one or more grooves 25 in the base member 3 for engaging one or more of the legs l9 and 20.

Referring to Figs. 1 and 3, it will be noted that the base 3 projects somewhat from the wall portion 2. The grooves 25 extend partially through this projecting portion of the base member 3 and are proportioned to snugly but slidably receive the legs I9 or 2%]. In the form illustrated, two

opposed grooves are provided, one for engaging each of the legs I9 and 20.

In order to connect the contact blades Iii detachably to the wiring associated with the panel I I, which may be the customary switchboard wiring, we prefer to place a plurality of contact jaws 26 in position to receive the contact blades I6 as the relay and its casing are moved into mounted position. Conveniently, these contact jaws may be mounted on the connecting section 22. As illustrated more particularly in Fig. 2, one or more contact jaws 26 may be mounted on an insulating block 2'! which, in turn, is attached to the connecting section in any suitable manner, as by a machine screw 28 which is screwed into a tapped opening 29 provided in the connecting section. Each contact jaw 26 is provided with a terminal member 351,- and'the resulting unit may be attached to the block 21 by means of a machine screw 3i. If desired, the insulating block 21 may be provided with extensions 32 which form shields around the contact jaws. A number of insulating blocks 21 each carrying one or more contact jaws may be required.

The terminal members 39 are connected permanently to the switchboard wiring and remain undisturbed no matter how often a relay and its casing is mounted on or removed from the panel I1. Although the contact members I and the contact jaws 26 are shown extending along a pair of parallel straight lines, it should be noted that the number, spacing and positions may be varied as desired.

When a large number of contact blades i8 and contact jaws re p ovided, the frictional resistance offered to nent and detachment of the relay and its casing becomes excessive. In a detachable flush mounted relay this particularly troublesome because oi the small portion of the relay exposed from the front of the panel 57 for handling purposes. In order to facilitate attachment and detachment of he relay and its casing, we provide one or in '"e jackscrews two being illustrated at opposed points on the flange member i. Each of these jackscrews is so mounted that it be rotated relative to the flange member but may not be moved axially relative thereto for substantial distance. To this end, the jackscrew be mounted in any known way on the flange as by providing the jecksc ew with a groove in which a collar 35 is peri nently mounted. Each jackscrew is threaded in a tapped opening 35 which extends through the reinforcing strap 23 and the bent end of one of the of the U-shaped bracket. Preferably the screw is or" such length that when the relay 't the jackscrew engages in the b before the contact es the contact jaws 25. According to the direction of rotation of the jackscrew the relay and its casing l are forceab-ly moved into or out of their mounted position.

It is believed that the operation of our invention is apparent from the foregoing description. When a relay and its casing l are to be inserted in mounted position, the

se member 3 is inserted through the openin l6 and immediately engages the leg 55 of the s -shaped bracket. These legs then guide the base member 3 from a position adjacent i138 rig is to a position adjacent the contact jaws and at the same time support the base member. As the contact blades it approach the contact jaws 26, the jackscrews engage the tapped openings 3% provided in he einiorcing straps and legs 19 and 28. At this screwdriver be applied to the jacksc ea s for rotating tiem in a direction such th t rlay and its casing i are advanced into mounted position against the resistance oiiere" by the contact jaw 2t to the contact blades l h n the relay casing l is in its fully mounted serve to hold it securely in this posl moving relay its casing from H, a screwdriver is applied each jec and rotated in a directio oh tha casing l tion. blades i5 screws 3;. l

t ie casing i may ,7

drawn from the It should noted 'th cket performs a number of di the first place, it serves as a i .,erticn of the relay casing i It also operates to support relay casing I its contents during the operation and removal thereof. Fur more, the U-shaped bracket serves a support for contact jaws 2t. Also, it should be noted that the stress applied by means of the jackscrews S3 is taken directly by the U-shaped bracket through the legs l9 and 26. This relieves the panel I! of stresses that otherwise would be applied to it.

Jhen the relay casing I is in its mounted position, the U-shaped bracket operating through the legs i9 and 2S and the jackscrews 33 hold th relay casing firmly in its attached position.

In those installations requiring a small number of contact blades l6 and contact jaws 26, it may be unnecessary to provide jackscrews 33 for forceabiy moving the relay casing I. In such cases the collar 35 may be omitted from the jackscrew assembly or the jackscrew itself may be entirely omitted, reliance being placed on the frictional resistance altered by the contact jaw and blade assembly and the legs i9 and 20 of the ll-shaped bracket for maintaining the relay casing in its counted position.

With the construction illustrated in Figs. 1, 2 and 3, the casing i is supported over a considerable area. That is, support is not only afiorded in the vicinity of the panel H, but the support extends to the base member 3 which rests on the leg is of the U-shaped bracket. In the particular construction shown the casing l is supported substantially at its extreme ends, thus affording a particularly rigid support. Moreover, because of the grooves 25, it is unnecessary to mount the caing in a single position, that is, the casing of 1 could be mounted when rotated 90 from position shown in Fig. l, or when rotated to other degree. In any position, complete guiding and supporting characteristics are provided by the illustrated construction.

The construction illustrated in Figs. 1, 2 and 3 may be adapted for projection type electrical instruments without substantial modification. For example, Fig. l, a relay casing l of the projection type is shown mounted on a panel IT. This panel may correspond to the panel I! of Fig. l, but as illustrated in Fig. 4, the panel serves as a cover for a trough or box having a base 3? a .d walls 33 to which the panel l1 may be ettac red in any desirable manner as by machine ws or hinges (not shown). A bracket having and 23', a connecting section 22' and nforcing straps 23 is attached to the panel [1' and corresponds to the U-shaped bracket of Figs.

1, Z and 3. The connecting section 22' carries one or more blocks 2? provided with contact jaws sim lar to those illustrated in Figs. 1, 2 3 Since the legs 29' and 25' do not embrace the casing pro of a projection type instrument, they may be substantially shorter than t provided for a flush mounted casing.

if further support is desired for the U-shaped bracket, pillars 39 may be attached to the box or trough box 3'! and machine screws 40 employed for attaching U-shaped bracket to the pillars 39.

When the cover or panel H is made removable to give access to wiring in the trough or box, the bracket may be entir1y supported on the pillars 39 by means of the screws 43. That the straps 23' or legs I9, 25!, need not be ecurcd to the cover or panel ll. With this arrangement the jaw assembly is held rigidly in position for wiring purposes despite the removal. of the cover or panel. After completion of the wiring, the panel or cover may be mounted on the box or trough.

Although the legs IS and 23' may be employed for guiding portions of the casing i in order to assure proper alignment of contacts in a manner analogous to that illustrated in Figs.

I tact blocks 21 l; 2 and 3, the construction of Fig. 4 employs a modified alignment structure. The casing I is provided with one or more projections 4 provided with openings for receiving one or more screws 33 which correspond to .the screws 33 of Figs. 1 and 2. Each screw 33 is provided with an extension M which is of slightly less diameter than the tapped opening provided in the reinforcing straps 23 and ends of the U-shaped bracket. Consequently, when the casing I is to be inserted in mounted position, it is placed over the panel II and advanced until the reduced extensions ii enter the tapped openings 36' provided in the reinforcing straps 23. The casing I then may be inserted further and the jackscrews 33 rotated to force the casing I into its mounted position. It is to be understood thatthe casing I carries contact blades corresponding to the blades It on the casing I for engaging contact jaws mounted on the con- Preferably the extensions 4] are of a length such that they enter the tapped openings 36 well before the contact blades carried by the blades I5 engage the jaws engaged by the blocks 21'. It is to be understood further that the panel I? is provided with one or more openings for receiving contact blades carried by the casing I but this opening or openings need not be sufiicient to pass the entire casing I.

Numerous modifications are possible in the arrangement of the contact blades and contact jaws. In some instances it may be desired to provide auxiliary contacts for connecting certain contact jaws when a detachable instrument is removed from its mounted position. A typical installation may require such circuit completing means for short-circuiting a current transformer which normally supplied energy to the instrument contained within the casing I. For such an installation, one or more auxiliary contacts 42 may be provided for automatically establishing the necessary circuits upon the withdrawal of the casing. This auxiliary contact may take the form disclosed in the Winter Patent No. 2,066,024. Furthermore, the contact jaw construction illustrated may include disconnect devices similar to that shown in the aforesaid Winter patent for opening predetermined circuits when desired.

It is obvious that numerous other modifications departing from the specific embodiments illustrated herein are possible. Therefore, we do not wish ourinvention to be restricted except as required by the appended claims when interpreted in view of the prior art.

We claim as our invention:

1. In a detachable electrical instrument installation, a panel having an opening, a detachable relay instrument having a base insertable in said opening in a predetermined direction for mounting on said panel, a U-shaped bracket positioned around the base of said instrument and having its ends extending from said panel for a substantial distance in said predetermined direction, said detachable relay instrument and said ends of said U-shaped bracket having slidably related inter-fitting male and female parts for confining movement of said relay instrument to said predetermined direction, contact means carried by said detachable relay instrument, and cooperating contact means carried by said U-shaped bracket and detachably engageable with said first-named contact means when said detachable relay instrument is in said mounted position.

2. In a detachable electrical instrument installation, a panel having an opening, a detachable relay instrument having a base insertable in said opening in a predetermined direction for mounting on said panel, a U-shaped bracket positioned around the base of said instrument and having its ends extending from said panel for a substantial distance in said predetermined direction, said detachable relay instrument and said ends of said U-shaped bracket having slidably related interfitting male and female parts for confining movement of said relay instrument to said predetermined direction, a plurality of contact members carried by said detachable relay instrument, said contact members being arranged in a predetermined pattern, and cooperating contact means for detachably engaging said contact members when said detachable relay instrument is in said mounted position, said cooperating contact means comprising a plurality of contact elements carried by said U- shaped bracket in said predetermined pattern for alignment with said contact members when said detachable relay instrument is in said mounted position.

3. In a detachable electrical instrument installation, a panel having an opening, a detachable relay instrument having a base insertable in said opening in a predetermined direction for mounting on said panel, said base having a recess extending in said predetermined direction, a U-shaped bracket positioned around the base of said instrument and having its ends extending from said panel for a substantial distance in said predetermined direction, one of said ends being slidably positioned in the recess provided in said base to form with said base slidably related interfitting male and female parts for confining movement of said relay to said predetermined direction, contact means carried by said detachable instrument, and cooperating contact means for detachably engaging said first-named contact means when said detachable instrument is in said mounted position, said cooperating contact means comprising contact elements carried by said U-shaped bracket.

4. In a detachable electrical instrument installation, a panel having an opening, a detachable relay instrument having a base insertable in said opening in a predetermined direction for mounting on said panel, a U-shaped bracket positioned around the base of said instrument and having its ends extending from said panel for a substantial distance in said predetermined direction, said detachable relay instrument and said ends of said U-shaped bracket having slidably related interfitting male and female parts for confining movement of said relay instrument to said predetermined direction, contact means carried by said detachable relay instrument, cooperating contact means carried by said U- shaped bracket and detachably engageable with said first-named contact means when said detachable relay instrument is in said mounted position, and means extending between said U- shaped bracket and said detachable relay instrument for moving said detachable relay instrument relative to said panel in said predetermined direction.

ROY M. SMITH. KOLMAN RIESZ. 

